Treponema spp. spirochetes and keratinopathogenic fungi isolated from keratomas in donkeys.

This research focuses on finding the cause of keratomas in donkeys. The researchers collected data from 167 donkeys, using a combination of clinical signs, radiography, and histopathological examination for diagnosis. The study found that keratinopathogenic fungi and a particular group of bacteria known as DD treponemes were both present in the keratomas. This is the first study to discover the presence of these two groups within keratomas.

Introduction to the study

• The research was commissioned to investigate the causes of keratomas in donkeys. Keratomas are abnormal masses of keratin that form between the stratum medium of a donkey’s hoof wall and the underlying third phalanx.
• Prior to this research, the cause of keratomas was unknown, although chronic irritation, infection and trauma have been suspected as contributors. Less is known about the role of microbial agents, particularly fungi and bacteria, in the development of these keratin masses.

Methodology of the research

• The study involves 167 donkeys diagnosed with keratomas based on clinical signs, radiography, and histopathological examination. Surgical excision was conducted on all lame donkeys unless euthanasia was advised.
• The researchers performed histopathologic examinations using Giemsa, periodic acid Schiff, and Young’s silver special histochemical stains, to identify the presence of fungal hyphae and spirochete bacteria in the keratin matter.
• They also carried out a polymerase chain reaction (PCR) test for treponeme bacteria on 10 keratoma lesions and 9 healthy pieces of hoof as a control comparison.
• Routine fungal culture tests and PCR tests for fungi were performed on 8 keratoma lesions and 8 healthy hoof samples.

Key findings of the study

• The study delivered some novel findings: it is the first to have detected the existence of digital dermatitis (DD) treponeme phylogroups and keratinopathogenic fungi in keratoma samples.
• The PCR test for treponeme bacteria found that all healthy donkey tissues were negative for DD treponeme phylogroups while 30% of the donkey keratoma samples tested positive for at least one of these groups.
• Routine fungal culture identified keratinopathogenic fungi in 12.5% of keratomas. The control healthy hoof samples only showed the presence of non-keratinopathogenic, environmental fungi.

Conclusion and Future Directions

• The discovery of both DD treponeme bacteria and keratinopathogenic fungi in keratoma samples raises questions about the potential role these microbes might play in the disease’s etiology.
• This is a preliminary study that needs to be followed by further research to assess the significance of these findings, particularly the role and impact of these microbes in the development of keratomas.